Dampening solution composition and offset printing method

Abstract

The present invention aims to provide a dampening solution composition that prevents the precipitation of calcium salts and other substances, suppresses roller peeling even during long-run printing, has stable printability without causing problems such as uneven density, decreased density, and poor transfer of printed materials that cause density fluctuations, and further reduces the number of roller cleaning cycles and shortens the roller cleaning time of the printing press. [Solution] A dampening solution composition containing a homopolymer of a specific aliphatic polycarboxylic acid and a salt thereof.

Description

[Technical Field]

[0001] This invention relates to a dampening solution composition used in offset printing. [Background technology]

[0002] Offset printing is a printing method that inherently utilizes the property that water and oil do not mix. The offset printing plate consists of a non-image area, which accepts water and repels oil-based ink, and an image area, which repels water and accepts oil-based ink. Efforts are made to increase the interfacial chemical difference between the non-image and image areas, thereby increasing the ink repulsion of the non-image area and the ink acceptance of the image area. To this end, various chemical substances have been added to the dampening solution used to form the non-image area, and diligent research has been conducted to maximize their performance.

[0003] To impart hydrophilicity to the non-image areas mentioned above, chemical substances such as nitric acid, phosphoric acid, phosphonic acid, sulfuric acid, hydrochloric acid, or salts thereof are used as additives. On the other hand, tap water or well water is usually used as dampening solution, and calcium ions contained in these react with the phosphoric acid, phosphonic acid, or salts thereof mentioned above, causing insoluble substances to precipitate. These precipitates can adhere to the rollers of the printing press and accumulate, hindering the normal transfer of ink and potentially interfering with printing.

[0004] Furthermore, the use of recycled paper, especially lightweight coated recycled paper with a coating layer containing a large amount of polyvalent metal salts such as calcium carbonate to increase whiteness, is increasing. When printing is performed continuously for long periods of time using these recycled papers, the dampening solution used for printing tends to dissolve the calcium carbonate contained in the surface coating layer of the recycled paper, and the calcium ion concentration in the dampening solution tends to increase. As mentioned earlier, an increase in calcium ion concentration can lead to reactions with acids and salts, resulting in significant precipitation of insoluble substances and further exacerbating the problem.

[0005] To solve these problems, Patent Document 1 proposes a dampening solution composition containing at least one selected from hydroxyaminocarboxylic acid-based chelating agents and iminodiacetic acid-based compounds, which can prevent the precipitation of calcium salts and other substances on the ink roll, as well as the adhesion and accumulation of inorganic pigment particles such as calcium carbonate, and provides a sufficient inhibitory effect against ink peeling on the ink roll.

[0006] Furthermore, Patent Document 2 proposes a dampening solution composition for lithographic printing containing an aminocarboxylic acid-based chelate compound, nitric acid or nitrate, and an EO·PO adduct compound of ethylenediamine, and describes that it suppresses the precipitation of calcium salts and the adhesion and accumulation of calcium carbonate and other materials on the ink roll.

[0007] However, while these chelating agents are effective in eliminating the precipitation of insoluble substances such as calcium ions, they are not sufficient and still inhibit the normal transfer of ink, causing problems such as roller peeling during printing, especially during long-run printing, and uneven density, reduced density, and poor transfer in printed materials that cause density fluctuations. Therefore, the applicant diligently investigated whether it would be possible to prevent calcium ions from reacting with the aforementioned salts and remaining as calcium ions in the dampening water, thereby preventing precipitation and the generation of insoluble substances. They discovered that by including a polymer composed of a specific compound, the generation of insoluble substances is suppressed even at high calcium ion concentrations, preventing them from adhering to and accumulating on the rollers of the printing press. Furthermore, Patent Documents 1 and 2 do not focus on calcium ion concentration, nor do they describe or suggest it. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2006-264251 [Patent Document 2] Japanese Patent Publication No. 2007-083664 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] Therefore, the present invention aims to provide a dampening solution composition that can prevent the precipitation of calcium salts and the like, suppress roller peeling even when long-run printing is performed, have stable printability without problems such as uneven density, decreased density, and poor transfer of the printed material that cause density fluctuations, and further reduce the number of roller cleaning cycles for the printing press and shorten the roller cleaning time. [Means for solving the problem]

[0010] As a result of diligent research, the inventors of the present invention discovered that the above objective can be achieved by including a homopolymer of aliphatic polycarboxylic acid and its salts, and thus completed the present invention.

[0011] In other words, the present invention is (1) A dampening solution composition containing a homopolymer of an aliphatic polycarboxylic acid represented by the following general formula (1) and a salt thereof,

[0012] [ka] (Here, in the formula, X, Y, and Z are each one of hydrogen, -CH3, -COOM, and -CH2-COOM, and at least one of X, Y, and Z is -COOM and -CH2-COOM. If Z is -COOM and -CH2-COOM, then X and Y are -CH2-COOM. Also, there is only one of X, Y, and Z that is -CH3. M and M 1 (where n is one of hydrogen, sodium, potassium, or ammonium, and may be the same or different; n is an integer between 3 and 1000.)

[0013] (2) The homopolymer of the aliphatic polycarboxylic acid and its salt are at least one selected from polymaleic acid, polyitaconic acid, polymesaconic acid, polyaconitic acid, polymethylene malonic acid, polycrotonic acid, polycitraconic acid and their salts, and the wetting water composition according to (1) is characterized by this., (3) Furthermore, the wetting water composition according to (1) or (2) is characterized by containing an acid, salts and a compound represented by the following general formula (2). R 1 -O-(C a H 2a-b (R 2 ) b O) n -H (2) (Here, in the formula, R 1 is an alkyl group having 1 to 4 carbon atoms, and R 2 is a hydrogen atom or a methyl group. a is an integer of 2 to 4. b is an integer of 0 to 2. n is an integer of 1 to 4.) (4) The wetting water composition according to (3) is characterized in that the acid is at least one selected from phosphoric acid, citric acid, gluconic acid, malic acid, succinic acid and maleic acid. (5) The wetting water composition according to (3) is characterized in that the salts are at least one selected from ammonium nitrate, phosphates, citrates, phthalates, p-toluenesulfonates. (6) An offset printing method characterized by including a printing process using a dilution obtained by diluting the wetting water composition according to (1) or (2) 25 to 200 times with water. is.

Effects of the Invention

[0014] According to the present invention, it becomes possible to prevent precipitation of calcium salts and the like. Even when long-run printing is performed, roller peeling is suppressed, and problems such as density unevenness, density reduction, and transfer failure of printed matter, which are factors causing density fluctuations, do not occur, and stable printing suitability is achieved. Furthermore, it is possible to provide a wetting water composition that can reduce the number of roller washings of a printing machine or shorten the roller washing time.

Modes for Carrying Out the Invention

[0015] Hereinafter, embodiments for carrying out the present invention will be described in detail. Note that this embodiment is merely one form for carrying out the present invention, and the present invention is not limited by this embodiment, and various modified embodiments are possible without departing from the gist of the present invention.

[0016] The moistening water composition of the present invention preferably contains a homopolymer of an aliphatic polycarboxylic acid represented by the following general formula (1) and a salt thereof.

[0017]

Chemical formula

[0018] In the general formula (1), X, Y, and Z are each preferably any one of hydrogen, -CH3, -COOM, and -CH2-COOM, and at least one of X, Y, and Z is more preferably -COOM and -CH2-COOM. When Z is -COOM and -CH2-COOM, X and Y are preferably -CH2-COOM. Also, among X, Y, and Z, the one that becomes -CH3 is limited to one. M and M 1 are any one of hydrogen, sodium, potassium, and ammonium, and may be the same or different, and among them, hydrogen and sodium are more preferable. n is an integer, the lower limit is 3, the upper limit is determined by the dissolution characteristics of the salt in the aqueous system, but it is preferably in the range of 3 to 1000, more preferably in the range of 10 to 500, and even more preferably in the range of 15 to 100.

[0019] The homopolymer of the aliphatic polycarboxylic acid represented by the general formula (1) and the salt thereof are specific homopolymers (M and M 1Examples of hydrogen atoms include polymaleic acid, polyitaconic acid, polymesaconic acid, polyaconic acid, polymethylenemalonic acid, polycrotonic acid, and polycitraconic acid, as well as their salts, with polyitaconic acid and its salts being more preferred, and polyitaconic acid being even more preferred. It is preferable to have at least one selected from these, and two or more may be used in combination.

[0020] Commercially available products can be obtained from companies such as Hakuto Chemical Co., Ltd., Parchem, Polysciences, Dayang Chem (Hangzhou), and Itaconix.

[0021] The content of the aliphatic polycarboxylic acid homopolymer and its salts is 0.1 to 10% by mass of the total dampening solution composition, more preferably 1 to 8% by mass, and even more preferably 2 to 5% by mass. Within this range, the precipitation of calcium salts and other substances is prevented, and the staining during printing is suppressed. If the content is less than 0.1% by mass, the precipitation prevention and staining suppression effects during printing are poor, and if it exceeds 10% by mass, the compatibility with water decreases, and precipitation or turbidity may occur.

[0022] Furthermore, it is preferable to include acids, salts, and compounds represented by the following general formula (2). R 1 -O-(C a H 2a-b (R 2 ) b O) n -H (2)

[0023] Specifically, examples of the aforementioned acids include organic acids such as citric acid, ascorbic acid, malic acid, tartaric acid, lactic acid, acetic acid, gluconic acid, succinic acid, maleic acid, hydroxyacetic acid, oxalic acid, malonic acid, levulinic acid, sulfanilic acid, p-toluenesulfonic acid, phytic acid, and organic phosphonic acid, and inorganic acids such as phosphoric acid, nitric acid, sulfuric acid, and polyphosphate. Among these, phosphoric acid, citric acid, gluconic acid, malic acid, succinic acid, and maleic acid are more preferred. It is preferable that at least one of these be selected, and two or more may be used in combination.

[0024] The acid content is 0.1 to 10% by mass of the total dampening solution composition, more preferably 0.3 to 5% by mass, and even more preferably 0.5 to 3% by mass. If it is less than 0.1% by mass, the surface finish will be reduced and it will be more prone to soiling, and if it exceeds 10% by mass, the pH will decrease, which may delay drying and accelerate wear of the image area of ​​the offset printing plate.

[0025] Examples of the aforementioned salts include alkali metal salts, alkaline earth metal salts, or ammonium salts of the above-mentioned organic acids and / or inorganic acids, and organic amine salts. Specifically, ammonium nitrate, sodium nitrate, phosphates, citrates, phthalates, and p-toluenesulfonates are preferred. Among these, ammonium nitrate, sodium nitrate, monoammonium phosphate, potassium hydrogen phthalate, and diammonium hydrogen citrate are more preferred. It is preferable that at least one of these be selected, and two or more may be used in combination.

[0026] The salt content is 0.1 to 10% by mass of the total dampening solution composition, more preferably 0.3 to 5% by mass, and even more preferably 0.5 to 3% by mass. If it is less than 0.1% by mass, the surface smoothing properties will decrease and it will become more prone to soiling, and if it exceeds 10% by mass, it will become less soluble in water, which may cause turbidity or separation.

[0027] In the above general formula (2), R 1 R is preferably an alkyl group having 1 to 4 carbon atoms. 1 Examples of such groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and t-butyl groups. From the viewpoint of increasing the solubility of diol compounds and suppressing blanket piling, n-butyl or t-butyl groups are particularly preferred. R 2 It is preferably a hydrogen atom or a methyl group, and more preferably a methyl group. 'a' is preferably an integer between 2 and 4. b is preferably an integer between 0 and 2. n is preferably an integer between 1 and 4, and particularly preferably an integer between 1 and 3.

[0028] Specific examples of compounds represented by the general formula (2) above include ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, ethylene glycol monopropyl ether, diethylene glycol monopropyl ether, triethylene glycol monopropyl ether, tetraethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monoisopropyl ether, triethylene glycol monoisopropyl ether, tetraethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monoisobutyl Ether, triethylene glycol monoisobutyl ether, tetraethylene glycol monoisobutyl ether, ethylene glycol monotertiary butyl ether, diethylene glycol monotertiary butyl ether, triethylene glycol monotertiary butyl ether, tetraethylene glycol monotertiary butyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, tetrapropylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monoethyl ether, tetrapropylene glycol monoethyl ether, propylene glycol monopropyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monopropyl ether, tetrapropylene glycol monopropyl ether, propylene glycol monoisopropyl ether, dipropylene glycol monoisopropyl ether, tripropylene glycol monoisopropyl ether,Examples include tetrapropylene glycol monoisopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, tetrapropylene glycol monobutyl ether, propylene glycol monoisobutyl ether, dipropylene glycol monoisobutyl ether, tripropylene glycol monoisobutyl ether, tetrapropylene glycol monoisobutyl ether, propylene glycol monotertiary butyl ether, dipropylene glycol monotertiary butyl ether, tripropylene glycol monotertiary butyl ether, and tetrapropylene glycol monotertiary butyl ether, among which ethylene glycol monotertiary butyl ether, propylene glycol monotertiary butyl ether, and 3-methoxy-3-methyl-1-butanol are more preferred. It is preferable that at least one of these be selected, and two or more may be used in combination.

[0029] The content of the compound represented by general formula (2) is 1 to 90% by mass relative to the dampening solution composition, more preferably 5 to 80% by mass, and even more preferably 10 to 70% by mass. If the content is less than 1% by mass, the surface tension will not decrease, and the surface will become prone to soiling. If the content exceeds 90% by mass, the compatibility with printing ink will increase, and the surface will become prone to over-emulsification.

[0030] The dampening solution composition of the present invention preferably further contains boric acids. Examples of boric acids include boric acid, diboron trioxide (anhydrous or hydrate), sodium tetraborate (anhydrous or hydrate), and sodium metaborate, with boric acid, diboron trioxide, and sodium tetraborate being more preferred. It is preferable that at least one of these be selected, and two or more may be used in combination.

[0031] The boric acid content is 0.1 to 10% by mass of the total dampening solution composition, more preferably 0.5 to 5% by mass, and even more preferably 1 to 4% by mass.

[0032] The dampening solution composition of the present invention may contain water-soluble organic solvents such as glycols and / or alcohols. Examples of glycols include propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, pentapropylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, butylene glycol, and hexylene glycol, with propylene glycol, dipropylene glycol, and tripropylene glycol being more preferred. Examples of alcohols include ethyl alcohol, isopropyl alcohol, n-propyl alcohol, t-butyl alcohol, isobutyl alcohol, t-amyl alcohol, benzyl alcohol, pentaerythritol, methoxyethanol, ethoxyethanol, and butoxyethanol. It is preferable that at least one of these be selected, and two or more may be used in combination.

[0033] The content of these water-soluble organic solvents is 1 to 50% by mass, and more preferably 10 to 40% by mass, relative to the dampening solution composition.

[0034] The dampening solution composition may contain a diol-type acyclic hydrocarbon compound having two OH groups, the shortest number of carbon atoms between the two OH groups being 2 to 6, and the total number of carbon atoms being 9. Examples of compounds with a minimum of 2 carbon atoms between OH groups include 1,2-nonanediol, 2,3-nonanediol, 3,4-nonanediol, 2-ethyl-1,3-hexanediol, 2-methyloctane-2,3-diol, 2-methyl-3,4-octanediol, 2,2,5-trimethyl-3,4-hexanediol, 3,3-dimethyl-1,2-heptanediol, 2-ethylheptane-1,2-diol, 3-ethyl-5-methyl-1,2-hexanediol, 2,3-dimethylheptane-2,3-diol, 3-ethyl-4-methylhexane-3,4-diol, 4-methyl-4,5-octanediol, and 3-isopropyl-4-methyl-2,3-pentanediol.Specifically, those with a minimum of 3 carbon atoms between OH groups are 2-butyl-2-ethyl-1,3-propanediol, 2,4-dimethylheptane-3,5-diol, 1,3-nonanediol, 2,4-nonanediol, 4,6-nonanediol, 2,4-dimethylheptane-1,3-diol, 2,4-dimethyl-3,5-heptanediol, 2,2-dimethyl-3,5-heptanediol, 2,6-dimethyl-3,5-heptanediol, 3,4-dimethyl-3,5-heptanediol, 2-methyloctane-3,5-diol, 2,6-dimethylheptane-3,5-diol, 2-[(1R)-1-methyl-3-methylbutyl]-1,3-propanediol, and 2-sec-butyl-2-ethyl Examples include ethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 2-hexylpropane-1,3-diol, 2-methyl-2-(1-methylbutyl)-1,3-propanediol, 2-methyl-2-pentyl-1,3-propanediol, 2-methyl-2,4-octanediol, 2-methyloctane-1,3-diol, 2,2-dipropyl-1,3-propanediol, 2,4,5-trimethylhexane-2,4-diol, 2,2,4,4-tetramethylpentane-1,3-diol, 2,4-dimethylheptane-2,4-diol, and 3-propyl-1,3-hexanediol. Examples of compounds with a minimum of 4 carbon atoms between OH groups include 1,4-nonanediol, 2,5-nonanediol, 3-methyloctane-1,4-diol, 4,6-dimethyl-2,5-heptanediol, 2-(1,2-dimethylpropyl)butane-1,4-diol, 2-isopentyl-1,4-butanediol, 2-ethyl-1,4-heptanediol, 2,2,3,3-tetramethyl-1,4-pentanediol, 2,4-dimethylheptane-1,4-diol, 4-methyloctane-1,4-diol, and 6,6-dimethyl-2,5-heptanediol.Examples of compounds with a minimum of 5 carbon atoms between OH groups include 1,5-nonanediol, 2,6-nonanediol, 2,4-diethyl-1,5-pentanediol, 4,6-dimethylheptane-1,5-diol, 2,6-dimethylheptane-1,5-diol, 2-isopropyl-1,5-hexanediol, 2-ethyl-1,5-heptanediol, 2,6-dimethyl-2,6-heptanediol, 3,3,5-trimethylhexane-1,5-diol, 6,6-dimethyl-1,5-heptanediol, and 7-methyl-1,5-octanediol. Examples of compounds with a minimum of 6 carbon atoms between OH groups include 1,6-nonanediol, 2-methyl-2,7-octanediol, 2,2,4-trimethyl-1,6-hexanediol, and 2,4,4-trimethyl-1,6-hexanediol. Among these, 2-ethyl-1,3-hexanediol, 2-butyl-2-ethyl-1,3-propanediol, and 2,4-diethyl-1,5-pentanediol are more preferred. It is preferable that at least one of these be selected, but two or more may be used in combination, and may also be used in combination with the water-soluble organic solvent.

[0035] The dampening solution composition of the present invention may contain a water-soluble polymer compound. Specific examples of water-soluble polymer compounds include gum arabic, starch derivatives (e.g., dextrin, enzymatically hydrolyzed dextrin, hydroxypropylated enzymatically hydrolyzed dextrin, carboxymethylated starch, phosphated starch, octenyl succinate starch, etc.), alginates, natural products and modified versions of cellulose derivatives (e.g., carboxymethylcellulose, carboxyethylcellulose, hydroxyethylcellulose, methylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, and their glyoxal-modified derivatives, etc.), polyvinyl alcohol and its derivatives, polyvinylpyrrolidone, polyacrylamide and its copolymers, polyacrylic acid and its copolymers, vinyl methyl ether / maleic anhydride copolymers, vinyl acetate / maleic anhydride copolymers, and other synthetic products. It is preferable that at least one of these be selected, and two or more may be used in combination.

[0036] The content of the water-soluble polymer compound is 0 to 5% by mass relative to the dampening solution composition, more preferably 0.1 to 3% by mass, and even more preferably 0.2 to 2% by mass.

[0037] The dampening solution composition of the present invention may contain a group consisting of sugars and glycerin. The sugars can be selected from monosaccharides, disaccharides, and oligosaccharides, and sugar alcohols obtained by hydrogenation are also included. Specific examples include D-erythrose, D-threose, D-arabinose, D-ribose, D-xylose, D-erythropentulose, D-allulose, D-galactose, D-glucose, D-mannose, D-talose, β-D-fructose, α-L-sorbose, 6-deoxy-D-glucose, D-glycero-D-galactose, α-D-allo-heptulose, β-D-altro-3-heptulose, saccharose, lactose, D-maltose, isomaltose, inulobiose, hyalubiouron, maltotriose, D,L-arabit, ribit, xylitol, D,L-sorbitol, D,L-mannitol, D,L-ijit, D,L-talitol, dulcit, arodulcit, maltitol, and reduced starch syrup. It is preferable that at least one of these be selected, and two or more may be used in combination.

[0038] The content of the group consisting of sugars and glycerin is 0 to 5% by mass relative to the dampening solution composition, more preferably 0 to 4% by mass, and even more preferably 1 to 3% by mass.

[0039] The dampening solution composition of the present invention may contain an ethylene oxide and propylene oxide addition condensate. As the ethylene oxide and propylene oxide addition condensate, a polypropylene glycol portion (hydrophobic group) with a molecular weight of 1,500 to 5,000, an ethylene oxide addition weight of 10 to 40% of the total molecule, and a molecular weight of 2,000 to 8,500 can be used. Among these, a polypropylene glycol portion with a molecular weight of 2,000 to 4,000 and an ethylene oxide addition weight of 10 to 20% of the total molecule is more preferable. The content of these addition condensates is 0 to 5% by mass relative to the dampening solution composition, more preferably 0.02 to 3% by mass, and even more preferably 0.1 to 2% by mass.

[0040] The dampening solution composition of the present invention may contain additives such as colorants, rust inhibitors (preservatives), and defoaming agents. Food colorants are preferably used as coloring agents. For example, yellow colorants include CI No. 19140 and 15985; red colorants include CI No. 16185, 45430, 16255, 45380, and 45100; purple colorant includes CI No. 42640; blue colorants include CI No. 42090 and 73015; and green colorant includes CI No. 42095.

[0041] Examples of rust inhibitors (preservatives) include benzotriazole, 5-methylbenzotriazole, thiosalicylic acid, benzimidazole (such as 2-4-thiazolylbenzimidazole) and its derivatives, benzoic acid, sorbic acid, halogenated phenols (such as 2,4,6-tribromophenol sodium salt), organic iodine (such as 4-chlorophenyl-3-iodopropagyl formal), nitriles (such as 2,4,5,6-tetrachloroisophthalonitrile), copper agents (such as 8-oxyquinoline copper), and trihaloallyls (3-bromo-2,3-diiodo- Examples include 2-propenylethylcarbonate, organic nitrogen sulfur compounds (thiocyano(methylenebisthianocyanate, etc.), N-haloalkylthioimide(N-tetrachloroethyl-thio-tetrahydrophthalimide, etc.), benzothiazole(2-thiocyanomethylthiobenzothiazole, etc.), thiazoline compounds, etc.), quaternary ammonium compounds (trimethoxysilyl-propyloctadecylammonium chloride, etc.), and pyridine compounds (2,3,5,6-cytochloro-4-(methylsulfonyl)-pyridine, etc.). Silicone defoaming agents are preferred as the defoaming agent, and both emulsified dispersion type and solubilized type can be used. In addition to the additives mentioned above, the following may also be included: corrosion inhibitors such as magnesium nitrate, zinc nitrate, calcium nitrate, potassium nitrate, and lithium nitrate; hardening agents such as chromium compounds and aluminum compounds; organic solvents such as cyclic ethers (e.g., 4-butyrolactone); and water-soluble surfactant organometallic compounds. The content of each of these additives is preferably 0.0001 to 1% by mass, relative to the total amount of the dampening solution composition.

[0042] The dampening solution composition of the present invention may contain a small amount of surfactant. As surfactants, anionic surfactants include fatty acid salts, abietins, hydroxyalkanesulfons, alkanesulfons, dialkylsulfosuccinates, linear alkylbenzenesulfons, branched alkylbenzenesulfons, alkylnaphthalenesulfons, alkylphenoxypolyoxyethylenepropylsulfons, polyoxyethylene alkylsulfophenyl ether salts, sodium N-methyl-N-oleyl taurate, disodium N-alkylsulfosuccinate monoamide, petroleum sulfons, hydrogenated castor oil, sulfated beef tallow, sulfated fatty acid alkyl esters, alkyl sulfates, polyoxyethylene Examples include ethylene alkyl ether sulfate salts, fatty acid monoglyceride sulfate salts, polyoxyethylene alkylphenyl ether sulfate salts, polyoxyethylene styrylphenyl ether sulfate salts, alkyl phosphate salts, polyoxyethylene alkyl ether phosphate salts, polyoxyethylene alkylphenyl ether phosphate salts, partially saponified styrene-maleic anhydride copolymers, partially saponified olefin-maleic anhydride copolymers, and naphthalene sulfonate formalin condensates. Among these, dialkyl sulfosuccinates, alkyl sulfate salts, and alkylnaphthalene sulfonates are preferably used. Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polystyrenephenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, pentaerythritol fatty acid partial esters, propylene glycol mono fatty acid partial esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyglycerin fatty acid partial esters, and polyoxyethylene castor oil. Examples include oils, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamides, N,N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters, trialkylamine oxides, and N-substituted pyrrolidones. Among these, polyoxyethylene alkylphenyl ethers, polyoxyethylene-polyoxypropylene block polymers, acetylene glycols and acetylene alcohols, acetylenediols and their ethylene oxide and / or propylene oxide adducts, and N-substituted pyrrolidones are preferably used. Examples of cationic surfactants include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives. Examples of amphoteric surfactants include alkylimidazolines. Furthermore, fluorinated surfactants can be mentioned. Examples of fluorinated anionic surfactants include perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, and perfluoroalkyl phosphate esters; examples of fluorinated nonionic surfactants include perfluoroalkyl ethylene oxide adducts and perfluoroalkyl propylene oxide adducts; and examples of fluorinated cationic surfactants include perfluoroalkyltrimethylammonium salts. Considering foaming issues and emulsification with the ink, the content of these surfactants is preferably 5% by mass or less, and 0.1 to 2% by mass is appropriate, relative to the total amount of the dampening solution composition.

[0043] The remainder is preferably water. The aforementioned components can be dissolved in water, preferably desalinated water, to obtain a dampening solution composition. This dampening solution composition may become non-uniform or the salts it contains may precipitate if exposed to low temperatures, so it may be diluted with water as appropriate.

[0044] When the dampening solution composition of the present invention is used on a commercial basis, it is often concentrated and sold as a product. During printing, the dampening solution composition is appropriately diluted with water and used as a diluent. The dampening solution composition is preferably diluted with water 1.1 to 1,000 times, and more preferably 25 to 500 times. If the dilution with water is less than 1.1 times, the components will not exert their full effect, and if it is greater than 1,000 times, over-emulsification may occur during printing, potentially impairing printability.

[0045] The dampening solution composition of the present invention can be used for various offset printing plates. For example, it can be suitably used for offset printing plates obtained by image exposure and development of a photosensitive offset printing plate (a printing plate that has been pre-treated to be photosensitive, called a PS plate) which has an aluminum plate as a support and a photosensitive layer on it. It can also be suitably used for offset printing plates (CTP plates) that are directly exposed with visible or infrared lasers. Specific examples include photopolymer type digital plates (e.g., Kodak LLC's Exthermo TP-W) and thermal positive type digital plates (e.g., Fujifilm Global Graphic Systems Co., Ltd.'s XP series). It can also be used suitably with processless offset printing plates. In processless offset printing plates, the image is directly exposed on the printing press with a visible or infrared laser, the non-image areas outside the exposed area are washed away with a dampening solution (diluent), and then printed using the normal offset printing method. Therefore, processless offset printing plates do not require post-processing steps such as development, washing, and rinsing solution treatment that were used with conventional PS plates and CTP plates, and thus these waste products are not generated. Examples of processless offset printing plates include Blue Earth (manufactured by Konica Minolta Business Solutions, Inc.), SUPERIA ZD-II, ZX (manufactured by Fujifilm Global Graphic Systems, Inc.), AZURA, ADAMAS (manufactured by Eco3 Japan Inc.), and SONORA XTRA CX2 (manufactured by Kodak LLC).

[0046] To use the aforementioned PS plates, CTP plates, and processless offset printing plates, an offset printing plate is prepared by exposing these plates to an image, and then the printed material is formed through a printing process using a general offset printing method.

[0047] Any paper suitable for conventional offset printing can be used as the substrate for the printed material of the present invention, but in particular, newsprint (uncoated paper), lightly coated paper, coated paper, art paper, etc., which are suitable for offset printing, are preferably used. [Examples]

[0048] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" refers to "parts by mass" and "%" refers to "percentage by mass".

[0049] [Preparation of dampening solution composition] Dampening solutions were prepared according to the formulations in Tables 1 and 2.

[0050] The materials used were as follows: PG: Propylene glycol TBA: t-butyl alcohol, manufactured by Kuraray Trading Co., Ltd. 85% Phosphate: Manufactured by Katakura Co-op Agri Co., Ltd. Malic acid: Manufactured by Fuso Chemical Industry Co., Ltd. Citric acid: Manufactured by Iwata Chemical Industry Co., Ltd. Ammonium nitrate: Manufactured by Sumitomo Chemical Co., Ltd. Monoammonium phosphate: Manufactured by Yoneyama Chemical Industries, Ltd. Potassium bituminate: Manufactured by Toyama Pharmaceutical Co., Ltd. Sodium nitrate: Manufactured by Sumitomo Chemical Co., Ltd. Ammonium dihydrogen citrate: Manufactured by Toyama Pharmaceutical Co., Ltd. PNB: Propylene glycol monobutyl ether Solfit:3-Methoxy-3-methyl-1-butanol AquaPaz DP-9: Polyitaconic acid, solid content approximately 45%, manufactured by Hakuto Co., Ltd. AquaPaz DP-11: Polyitaconic acid, solid content approximately 30%, manufactured by Hakuto Co., Ltd. DPTA-OH: 2-hydroxypropane-1,3-diaminetetraacetic acid, manufactured by Kirest Co., Ltd. ADA:N-(carbamoylmethyl)iminodiacetic acid, manufactured by Dojin Chemical Laboratories Co., Ltd. DPTA: Diethylenetriaminepentaacetic acid, manufactured by Kirest Co., Ltd. HPC: Hydroxypropylcellulose, manufactured by Nippon Soda Co., Ltd. Pluronic® TR-701: Ethylene oxide and propylene oxide addition condensate, manufactured by ADEKA Corporation. Pluronic® L-31: Ethylene oxide and propylene oxide addition condensate, manufactured by ADEKA Corporation. Octanediol (2-ethyl-1,3-hexanediol): Manufactured by KH Neochem Co., Ltd. Concentrated glycerin: Manufactured by Chuo Kasei Co., Ltd. Benzotriazole: Manufactured by Fuji Chemical Trading Co., Ltd. Slaoff 40G: Manufactured by Osaka Gas Chemical Co., Ltd. Dispanol WI-115: Manufactured by NOF Corporation Surfinol 440: Manufactured by Nisshin Chemical Industry Co., Ltd. N-octyl-2-pyrrolidone: Manufactured by Tokyo Chemical Industry Co., Ltd.

[0051] [Table 1]

[0052] [Table 2]

[0053] [Calcium ion concentration] For the dampening water compositions of Examples 1-11 and Comparative Examples 1-9, 80 mL of dampening water diluted 50 times with distilled water was added to 100 g of commercially available red ink (UV OL HLE TS red, manufactured by Tokyo Ink Co., Ltd.). The mixture was then stirred at 100 rpm / min for 15 minutes in a Surland emulsification tester to force emulsification. After that, the excess dampening water was collected, and the calcium ion concentration (mg / L) was measured by ion chromatography. The calcium ion concentration (mg / L) of the diluted dampening water before emulsification was also measured by the same method. A higher calcium ion concentration (mg / L) in the excess emulsified dampening solution after forced emulsification was considered to indicate a higher amount of residual calcium ions in the excess emulsified dampening solution, which was deemed a positive result. The results are shown in Tables 3 and 4.

[0054] [Inhibition of precipitation] The excess emulsified dampening solution used to achieve the above calcium ion concentration was placed in a test tube, and the contents of the test tube were observed after standing for 24 hours. The presence or absence of white precipitate was evaluated in two stages: ○: no precipitate observed, ×: precipitate observed. The results are shown in Tables 3 and 4.

[0055] From the evaluation of calcium ion concentration and precipitation inhibition described above, it was confirmed that the higher the calcium ion concentration, the better the precipitation inhibition. This is presumed to be because it suppresses the precipitation of minerals (such as calcium) in the water and calcium salts dissolved from the ink, allowing the calcium ions to remain in the water.

[0056] [Density fluctuations] Using a printability evaluation machine (manufactured by MHI Solution Technologies, Ltd.), the dampening water compositions of Examples 1-11 and Comparative Examples 1-9 were diluted 50 times with distilled water. Printing was performed using red ink (Gaia Red, manufactured by Tokyo Ink Co., Ltd.) at a printing speed of 450 m / min (equivalent to approximately 700 rpm on a full-size A-size print press) with the water dial fixed at 50. Measurement was started when the ink film thickness on the ink mixing roller stabilized at 2-3 μm using the infrared irradiation ink film thickness meter equipped on the printability evaluation machine. The water dial was increased by 3 every 10 minutes to evaluate the fluctuation of the ink film thickness on the ink mixing roller (maximum value of the water dial is 99). The less the fluctuation of the ink film thickness, the less the concentration fluctuation, and the better the result. The ink film thickness was evaluated on a 5-point scale: ◎: No change in ink film thickness was observed even when the water dial was raised to 90 or higher, ○: Change in ink film thickness was observed when the water dial was set to 80 or higher but less than 90, △: Change in ink film thickness was observed when the water dial was set to 75 or higher but less than 80 (no practical problem), ×: Change in ink film thickness was observed when the water dial was set to 70 or higher but less than 75, ××: Change in ink film thickness was observed when the water dial was set to less than 70. The results are shown in Tables 3 and 4.

[0057] [Actual device testing and evaluation] For the dampening solution compositions of Examples 2, 6, 9, 10, and 11, as well as Comparative Examples 1, 3, 7, 8, and 9, actual press printing tests were conducted under the following conditions, and the calcium ion concentration of the dampening solution was measured after one week. The dampening rollers of the printing press were thoroughly cleaned before each actual press printing test. Dampening solution compositions that were not subjected to actual press printing tests are indicated with "-". A print was judged to be of higher quality if the calcium ion concentration in the dampening solution one week after the print test was higher than the calcium ion concentration at the start of the print test. The results are shown in Tables 3 and 4. Printing press: Ryobi MHI Graphic Technology Co., Ltd. RMGT11 flatbed 8-color press (full size), high-sensitivity UV printing. Print rotation speed: 14000 sph Printing inks: UV OL HLE TS manufactured by Tokyo Ink Co., Ltd. (black, cyan, magenta, yellow) Paper: OK Coat L, manufactured by Nippon Paper Industries Co., Ltd. Dampening solution: Each dampening solution composition is diluted 50 times with tap water to prepare it (automatically dispensed during printing according to the dampening solution device settings).

[0058] The above-mentioned actual machine printing test was continued (long-run printing during normal printing operations), and roller accumulation and roller cleaning were evaluated. The results are shown in Tables 3 and 4.

[0059] [Roller deposition] Two weeks later, we visually inspected the ink mixing roller and dampening roller (rubber roller) of the printing press to see if any calcium deposits were present. The deposits on the ink mixing roller and wetting roller were evaluated on a three-point scale: ○: none at all, △: some deposits present but no problem with printability, and ×: a large amount of deposits present, resulting in roller peeling and uneven density in the printed material.

[0060] [Roller cleaning] For those that received a "○" or "△" rating during the roller accumulation evaluation described above, further printing was performed, and the presence and condition of roller cleaning were evaluated. As a guideline, those where more than two months passed before roller cleaning were considered good. Roller cleaning was evaluated in two stages: ○: No cleaning was required for more than two months, and when the accumulation was cleaned, it was easy to clean and the time was reduced; ×: Those that received a "×" in the roller accumulation evaluation described above, or those where roller peeling due to accumulation occurred in less than two months, and the time required to clean the accumulation was the same as or longer than before. The presence and status of roller cleaning are described in Tables 3 and 4.

[0061] [Table 3]

[0062] [Table 4]

[0063] Table 3 clearly shows that Examples 1-6 have a higher calcium ion concentration in the excess dampening water after forced emulsification, a larger amount of calcium ions remaining in the excess dampening water, and no white precipitate at all, compared to Comparative Examples 1-3. This indicates that the dampening water compositions of Examples 1-6 effectively retain calcium ions in the water, suppressing precipitation as calcium salts. Furthermore, the results of concentration fluctuations using a printability evaluation machine clearly show that even when the water dial is increased, i.e., when the amount of dampening water is excessive, the ink film thickness fluctuates little, and the print density remains stable. In addition, in actual machine testing, the calcium ion concentration after one week of printing was higher than at the start of printing, a larger amount of calcium ions remained in the dampening water used, the deposition on the rubber roller after two weeks was good, and no defects occurred in the printed material. Moreover, the rollers were less prone to depositing calcium ions for more than two months, allowing printing to continue without cleaning, and the rollers were easier to clean, resulting in reduced cleaning time. Comparative Examples 1-3, which did not contain aliphatic polycarboxylic acid homopolymers or their salts, showed lower calcium ion concentrations in the excess dampening water after forced emulsification compared to Examples 1-6, resulting in precipitate formation. Furthermore, in the results of concentration fluctuations using a printability evaluation machine, increasing the water dial caused fluctuations in ink film thickness and unstable print density. In addition, in actual machine testing of Comparative Examples 1 and 3, the calcium concentration after one week of printing remained almost unchanged from the start of printing, resulting in few residual calcium ions that precipitated as calcium salts. After two weeks, roller peeling occurred, leading to defects in the printed material and necessitating roller cleaning. The roller cleaning time was also the same as before. The dampening water compositions containing chelating agents similar to those in Patent Documents 1 and 2, used in Comparative Examples 4-6, showed low calcium ion concentrations in the excess dampening water and the formation of white precipitates. In other words, it is clear that the effect of retaining calcium ions in water is small, and they precipitate as calcium salts. Furthermore, the results of density fluctuations measured by the printability evaluation machine also showed that increasing the water dial caused fluctuations in ink film thickness and unstable print density. Example 7, which contains a small amount of aliphatic polycarboxylic acid homopolymer and its salt, shows a high calcium ion concentration and no white precipitate at all, and the results of concentration variation using a printability evaluation machine clearly indicate good performance. Furthermore, Example 8, which contains an excessive amount of aliphatic polycarboxylic acid homopolymer and its salt, also shows a high calcium ion concentration and no white precipitate at all, and the results of concentration variation using a printability evaluation machine clearly indicate excellent performance. Examples 9-11 clearly show better results than Comparative Examples 7-9, with higher calcium ion concentrations in the excess dampening water after forced emulsification, a larger amount of calcium ions remaining in the excess dampening water, and no white precipitates observed. Furthermore, the results of concentration fluctuations using a printability evaluation machine clearly show that even when the water dial is increased, i.e., when the amount of dampening water is excessive, the ink film thickness fluctuates little and the print density remains stable. Moreover, in actual machine testing, the calcium ion concentration after one week of printing was higher than at the start of printing, a larger amount of calcium ions remained in the dampening water used, the deposition on the rubber rollers after two weeks was good, and no defects occurred in the printed materials. Furthermore, there was little roller deposition for more than two months, allowing printing to continue without cleaning, and roller cleaning was easier, resulting in reduced cleaning time. Comparative Examples 7-9, which did not contain aliphatic polycarboxylic acid homopolymers or their salts, showed lower calcium ion concentrations in the excess dampening water after forced emulsification compared to Examples 9-11, resulting in precipitate formation. Furthermore, in concentration fluctuation tests using a printability evaluation machine, increasing the water dial caused fluctuations in ink film thickness and unstable print density. In addition, in actual machine testing of Comparative Examples 7-9, the calcium concentration after one week of printing remained almost unchanged from the start of printing, resulting in few residual calcium ions that precipitated as calcium salts. After two weeks, roller peeling occurred, leading to print defects and necessitating roller cleaning. The roller cleaning time was also the same as before. [Industrial applicability]

[0064] Therefore, since the precipitation of calcium salts on the rollers can be suppressed, roller peeling is reduced, density unevenness, density reduction, and transfer failures that cause density fluctuations in printed materials are suppressed, enabling stable long-run printing. Furthermore, in addition to significantly reducing the number of roller cleanings, it is also possible to shorten the roller cleaning time, which contributes to improved work efficiency and reduced burden on workers.

Claims

1. A dampening solution composition containing a homopolymer of an aliphatic polycarboxylic acid represented by the following general formula (1) and a salt thereof. 【Chemistry 1】 (Here, X, Y, and Z are hydrogen, -CH, respectively) ３ , -COOM and -CH ２ -COOM is one of the following, and at least one of X, Y, and Z is -COOM and -CH ２ -COOM. Z is -COOM and -CH ２ -If it is COOM, then X and Y are -CH ２ -COOM. Also, one of X, Y, and Z is -CH ３ There is only one such case. M and M １ (where n is one of hydrogen, sodium, potassium, and ammonium, and may be the same or different; n is an integer in the range of 3 to 1000.)

2. The dampening solution composition according to claim 1, characterized in that the aliphatic polycarboxylic acid homopolymer and its salt are at least one selected from polymaleic acid, polyitaconic acid, polymesaconic acid, polyaconic acid, polymethylenemalonic acid, polycrotonic acid, and polycitraconic acid and their salts.

3. Furthermore, the dampening solution composition according to claim 1 or 2 is characterized by containing acids, salts, and compounds represented by the following general formula (2). R １ -O-(C ａ H ２ａ－ｂ (R ２ ) ｂ O) ｎ -H (2) (Here, in the formula, R １ R is an alkyl group having 1 to 4 carbon atoms. ２ (where a is a hydrogen atom or a methyl group; a is an integer between 2 and 4; b is an integer between 0 and 2; n is an integer between 1 and 4.)

4. The dampening solution composition according to claim 3, characterized in that the acid is at least one selected from phosphoric acid, citric acid, gluconic acid, malic acid, succinic acid, and maleic acid.

5. The dampening solution composition according to claim 3, characterized in that the salts are at least one selected from ammonium nitrate, phosphate, citrate, phthalate, and p-toluenesulfonate.

6. An offset printing method characterized by including a printing step of using a diluted solution obtained by diluting the dampening solution composition described in claim 1 with water 25 to 200 times.

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